1. Field of the Invention
The present invention relates to electrical safety, more particularly, to a method of protecting workers from electrical arcs.
2. Description of the Related Art
When working on electrical equipment, there is always the possibility of an occurrence of an electrical arc. Consequently, people working on such environments wear garments specifically designed to protect against such arcing. However, these garments do not protect other equipment nor do they protect persons not wearing the garments that are doing other work in the vicinity. Arc protective blankets and curtains were developed to provide secondary protection for the worker and equipment. The blanket or curtain is hung between the equipment being worked on and the individual and/or other areas to be protected. These blankets are typically composed of one or more layers of a cloth woven from a para-aramid fiber or meta-aramid fiber, such as Dupont's Kevlar or Dupont's Nomex. The strength of the cloth allows the blanket to deflect and/or absorb the energy of an arc, diverting the energy away from the area being protected. Typically, the blanket is damaged or destroyed in the process. Typically, the strength of the blanket is determined by the number of layers of fabric. The greater the number of fabric layers in the blanket, the greater the strength of the blanket to deflect the energy of the electric arc. However, there is also a proportionate increase in blanket weight, space necessary for storage, and cost.
Another deficiency of blankets or curtains composed of fabrics containing para-aramid and meta-aramid fibers is that, at sufficiently high temperatures, temperatures that can easily be reached by electrical arcs, the material will burn and smoke. These materials are fire-retardant, so that when the catalyst (heat or fire) is removed, the fire and smoke cease. However, the fire and smoke that are generated can cause significant problems, particularly in confined spaces, such as underground (utility) vaults.
Another deficiency of these blankets or curtains is that the appearance and strength of these materials when exposed to the sun's ultraviolet (UV) light will degrade, thus reducing its protective characteristics. Thus, careful storage and care are required to minimize the blankets' UV light exposure in order to reduce premature aging and potential failure of these blankets.
Another deficiency of these blankets is susceptibility to degradation when exposed to one or more of a variety of chemical agents that are typical to the environment in which the blankets are used. Exposure to chemical agents such as diacetone or paint thinner can degrade the strength of the blanket, reducing its protective characteristics. Additionally, special care must be taken when cleaning these blankets because these materials are affected by many soaps, cleaning agents, fabric softeners, etc., used in laundering.
The blankets are fitted with a means for attachment. Such means can include straps with buckles or clamps. The straps, typically of Dupont Kevlar, are stitched to the blanket so that they extend from the edges. Buckles or clamps are sewn into the free end. The straps can be made adjustable. Another means for attachment include eyelets through which straps or other line can be threaded. Blankets are also made with integral handles for ease in carrying and hanging.